• Boolean negation and non-conservativity I: Relevant modal logics 

      Øgaard, Tore Fjetland (Journal article; Peer reviewed, 2020)
      Many relevant logics are conservatively extended by Boolean negation. Not all, however. This paper shows an acute form of non-conservativeness, namely that the Boolean-free fragment of the Boolean extension of a relevant ...
    • Boolean negation and non-conservativity II: The variable-sharing property 

      Øgaard, Tore Fjetland (Journal article; Peer reviewed, 2020)
      Many relevant logics are conservatively extended by Boolean negation. Not all, however. This paper shows an acute form of non-conservativeness, namely that the Boolean-free fragment of the Boolean extension of a relevant ...
    • Boolean negation and non-conservativity III: the Ackermann constant 

      Øgaard, Tore Fjetland (Journal article; Peer reviewed, 2020)
      It is known that many relevant logics can be conservatively extended by the truth constant known as the Ackermann constant. It is also known that many relevant logics can be conservatively extended by Boolean negation. ...